FIG. 17 is a block diagram of an image recording and reproducing apparatus for monitoring by using a hitherto well-known image switching device. In FIG. 17, image signals taken out from plural cameras CM1 to CMN are sequentially switched by control signals from a control circuit 7 in every frame by a switch (SW) 1 as a frame switcher, and put into a recording signal processing circuit 3. In the recording signal processing circuit 3, input image signals are processed by continuity hold in odd and even fields and subcarriers, and are converted into recording signals to be recorded in a VTR 6. The recording signals taken out from the recording signal processing circuit 3 are put into a superimposing circuit 4, while the camera number identification signal issued from the control circuit 7 is fed into the superimposing circuit 4, in which it is superimposed in a vertical blanking period of the recording signal. The camera number identification signal taken out from the control circuit 7 is an identification signal synchronized with the switch 1 and corresponding to the output side camera. The recording signal on which the camera number identification signal is superimposed is delivered from the superimposing circuit 4, and is recorded in the VTR 6.
On the other hand, by a switch (SW) 2 independent of the switch 1, an image signal of other camera than the one for recording into the VTR 6 can be selected and monitored by the monitor 5. Reference numeral 8 shows switch (SW)1 and switch (SW) 2 as one switching device.
An example of image switching device and image outputting device is disclosed in Japanese Laid-open Patent No. 5-83632. This device includes a frame switcher for switching image signals from plural television cameras in every frame, and sending out.
In the conventional image switching device, when recording or monitoring the image signals obtained from plural cameras, a frame switcher is required in order to select image signals from a desired cameral sequentially. Or when monitoring a desired camera always while recording image signals from plural cameras, a frame switcher of an independent system is needed. That is, the frame switcher is required to have two systems, that is, a switch for selecting sequentially and a switch for selecting an image output from a desired camera arbitrarily.
Further, to synchronize a plurality of cameras, a synchronous timing signal must be supplied in each camera independently, or a memory or the like must be provided in the frame switcher to synchronize them.